PTH Vin Single

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1 NEW Product PTH000.Vin Single Application Note 1 1. Introduction. System Interface Information Input Capacitor Output Capacitance (Optional) Tantalum Ceramic Capacitors Capacitor Table. Mechanical Information Mechanical Outline Drawings Pin-out Table Pin Description Ground Track V in Inhibit V o Adjust V out. Packaging Information Packaging Labels and Part Numbering Sequence. Safety Information Safety Standards and Approvals Fuse Information Safety Considerations. Operating Information Overtemperature Protection (OTP) Overcurrent Protection Soft-Start Power-up 7. Feature Set Adjusting the Output Voltage 7 Output ON/OFF Inhibit 7 Pre-bias Start-up Capability 8 8. Thermal Information Thermal Reference Points 9 Safe Operating Curve 9 Thermal Test Set-up 9 9. Use in a Manufacturing Environment Recommended Land Pattern Auto-Track Auto-Track Function 10 How Auto-Track Works 10 Typical Applications 10 Notes on the Use of Auto-Track 11 1 Rev. 0 / 1 December 00 File Name: an_pth000.pdf

2 PTH000 Single Series Application Note 1 1. Introduction The PTH family of non-isolated, wide-output adjust power modules from Artesyn Technologies are optimized for applications that require a flexible, high performance module that is small in size. These products are part of the Point-of-Load Alliance (POLA), which ensures compatible footprint, interoperability and true second sourcing for customer design flexibility. The POLA is a collaboration between Artesyn Technologies, Astec Power and Texas Instruments to offer customers advanced non-isolated modules that provide the same functionality and form factor. Product series covered by the alliance includes the PTHxx00W ( A), PTHxx00W (10 A), PTHxx010W (1/1 A), PTHxx00W (/18 A), and the PTHxx00W (0/ A). From the basic, Just Plug it In functionality of the A modules, to the 0 A rated feature-rich PTHxx00W, series these products were designed to be very flexible, yet simple to use. The features vary with each product series. Table 1 provides a quick reference to the available features by series and input bus voltage. For simple point-of-use applications, the PTHxx00W series provides operating features such as an ON/OFF inhibit, output voltage trim, pre-bias start-up (./ V input only), and overcurrent protection. The PTHxx00W (10 A), and PTHxx010W (1/1 A) series add an output voltage sense, and margin up/down controls. The higher output current, PTHxx00W and PTHxx00W series also incorporates overtemperature and shutdown protection. All of the products referenced in Table 1 include Auto-Track. This is a feature unique to the PTH family, and was specifically designed to simplify the task of sequencing the supply voltage in a power system. These and other features are described in the following sections. SERIES INPUT ADJUST ON/OFF OVER- PRE-BIAS AUTO- MARGIN OUTPUT THERMAL I OUT BUS TRIM INHIBIT CURRENT STARTUP TRACK * UP/DOWN SENSE SHUTDOWN. V A PTHxx00 V A 1 V A./ V 10 A PTHxx00 1 V 10 A./ V 1 A PTHxx010 1 V 1 A./ V A PTHxx00 1 V 18 A./ V 0 A PTHxx00 1 V A Table 1 - Operating Features by Series and Input Bus Voltage RoHS Compliance Ordering Information PTH000WAST To order Pb-free (RoHS compatible) surface-mount parts replace the mounting option S with Z, e.g. PTH000WAZT. To order Pb-free (RoHS compatible) through-hole parts replace the mounting option H with D, e.g. PTH000WADT. *Auto-track is a trade mark of Texas Instruments

3 Application Note 1. System Interface Information.1 Input Capacitor The recommended input capacitance is determined by 00 ma rms minimum ripple current rating and 100 µf minimum capacitance. Ripple current and <00 mω equivalent series resistance (ESR) values are the major considerations, along with temperature, when designing with different types of capacitors. Tantalum capacitors have a recommended minimum voltage rating of x (max. dc voltage ac ripple). This is standard practise for tantalum capacitors to ensure reliability.. Output Capacitance (Optional) The recommended ESR of the output capacitor is equal to or less than 00 mω. Electrolytic capacitors have marginal ripple performance at frequencies greater than 00 khz but excellent low frequency transient response. Above the ripple frequency, ceramic capacitors are necessary to improve the transient response and reduce any high frequency noise components apparent during higher current excursions...1 Tantalum/Ceramic Capacitors Tantalum capacitors are acceptable on the output bus. Tantalum, Os-con, or ceramic capacitor types are recommended for applications where ambient temperatures fall below 0 C. Ceramic capacitors may be used instead of electrolytic types on both the input and output bus. The input bus must have the minimum amount of capacitance. A single 10 µf ceramic capacitor may also be used on the output bus to reduce output ripple... Capacitor Table Table identifies the characteristics of capacitors from a number of vendors with acceptable ESR and ripple current (rms) ratings. The number of capacitors required at both the input and output buses is identified for each capacitor type. This is not an extensive capacitor list. Capacitors from other vendors are available with comparable specifications. Those listed are for guidance. The RMS ripple current rating and ESR (at 100 khz) are critical parameters necessary to insure both optimum regulator performance and long-term reliability. CAPACITOR VENDOR/ SERIES CAPACITOR CHARACTERISTICS Table - Recommended Input/Output Capacitors QUANTITY (ESR) EQUIVALENT MAX RIPPLE PHYSICAL OPTIONAL VENDOR WORKING VALUE SERIES AT 8ºC SIZE (mm) INPUT OUTPUT PART VOLTAGE (µf) RESISTANCE CURRENT (Irms) (L X W) BUS BUS NUMBER Panasonic FC V Ω 0 ma 8 x EEVFC1E101P (SMT) WA (SMT) 10 V Ω 800 ma 8. x EEFWA1A11P Panasonic FC 1 V Ω ma 10 x EEUFC1C1 FK (SMT) 1 V Ω 00 ma 8 x EEVFK1C1P United Chemi-Con FS 10 V Ω 100 ma. x FS100M PXA (SMT) 10 V Ω 0 ma 8 x PXA10VC11MH80TP MVZ (SMT) 1 V Ω 0 ma 8 x MVZVC1MH10TP PS 10 V Ω 0 ma 8 x PS70MH11 Nichicon WG (SMT) V Ω 70 ma 10 x UWG1V101MNR1GS NA 10 V Ω 10 ma 8 x PNA1A11M1 PM V Ω 0 ma 10 x UPM1E11MPH SANYO Os-con : SVP (SMT) 10 V Ω >00 ma 7 x SVP10M SP 1 V Ω >800 ma. x SPS100M TPA 10 V Ω >100 ma 7. x TPA100M AVX Tantalum 10 V Ω >1090 ma 7. x. 1 1 TPSD107M010R0100 TPS 10 V Ω >11 ma 7. x. 1 1 TPSV7M010R0100 Kemet T0 10 V Ω 100 ma 7. x T0D107M010AS T9 10 V Ω >1100 ma 7. x T9X107M010AS Sprague 9D/ 10 V Ω 1100 ma 7. x D17X0010CT 9D 10 V Ω >1000 ma 7. x D17X0010DT TDK Ceramic XR. V Ω >10 ma. x.8 CXR0J7KT/MT Murata Ceramic. V Ω >1000 ma. x.8 GRMER0J7M/. XR 110 Case

4 PTH000 Single Series Application Note 1. Mechanical Information.1 Mechanical Outline Drawings 0.00 (1.) (.10) TOP VIEW Dimensions in Inches (mm) Tolerances (unless otherwise specified) Places ±0.00 (±0.7) Places ±0.010 (±0.) 0.00 (1.) (19.0) 0. (8.0) SIDE VIEW Figure 1 - Plated Through-Hole Mechanical Drawing (.10) 0.70 (19.0) 1 TOP VIEW 0.00 (1.) (9.) (1.7) 0.00 (1.) (1.7) (9.) MAX. 0. (8.0) max.* 0.10 (.) SIDE VIEW 0.00 (1.0) Places Lowest Component min. (0.) Bottom side Clearance (1.78) (Standoff Shoulder) Host Board *After solder reflow on customer board Solder Ball 0.00 (1.0) Place. Pin Description..1 Ground This is the common ground connection for the V in and V out power connections. It is also the 0 Vdc reference for the control inputs... Track This is an analog control input that allows the output voltage to follow another voltage during powerup and power-down sequences. The pin is active from 0 V up to the nominal set-point voltage. Within this range the module s output will follow the voltage at the Track pin on a volt-for-volt basis. When the control voltage is raised above this range, the module regulates at its nominal output voltage. If unused, this input may be left unconnected. For further information consult section V in The positive input voltage power node to the module, which is referenced to common... Inhibit The Inhibit pin is an open-collector/drain negative logic input that is referenced to. Applying a low level ground signal to this input disables the module s output and turns off the output voltage. When the Inhibit control is active, the input current drawn by the regulator is significantly reduced. If the Inhibit pin is left open-circuit, the module will produce an output whenever a valid input source is applied... V o Adjust A 0.1 W, 1% tolerance (or better) resistor must be connected directly between this pin and pin 1 () pin to set the output voltage to a value higher than 0.8 V. The temperature stability of the resistor should be 100 ppm/ C (or better). The set point range for the output voltage is from 0.8 Vdc to. Vdc. The resistor required for a given output voltage may be calculated from the following formula. If left open circuit, the module output will default to its lowest output voltage value. Dimensions in Inches (mm) Tolerances (unless otherwise specified) Places ±0.00 (±0.7) Places ±0.010 (±0.). Pin-out Table Figure - Surfact Mount Mechanical Drawing PIN CONNECTIONS The specification table gives the preferred resistor values for a number of standard output voltages... V out The regulated positive power output with respect to the node. PIN NUMBER FUNCTION 1 Ground Track V in Inhibit V o adjust V out Table - Pin Connections

5 Application Note 1. Packaging Information.1 Packaging The PTH000 are available in trays of 8 units and tape and reel format in quantities of 0 units per reel. Tray and tape dimensions including pick point are shown in Figures and.. Labels and Part Numbering Sequence All units in the series will be clearly marked to allow ease of identification for the end user. Figure gives details of all the models. SERIES TYPE (POINT OF LOAD ALLIANCE) POCKET SIZE 0.17 (.00) (.00) ø ( ) (1.7) 0.79 (0.0) 1.91 (0.0) 1.7 (.00 ±0.0) Ao (1.08) Bo (.1) Ko (9.09) (.1) Bo PTH PTH 000 ZYWWBR (1.70.1) (.00) ø ( ) (0.1) ZYWWBR (1.08) 0.8 (9.09) Ko BOM REV. WEEK CODE MAN.LOCATION/YEAR CODE MODEL TYPE Ao COMPONENTS SHALL BE PACKAGED IN ANTI-STATIC MATERIAL PER EIA-1 PACKAGING MATERIAL STANDARDS FOR ESD SENSITIVE ITEMS. Dimensions in Inches (mm) Tolerances (unless otherwise specified) Places ±0.00 (±0.1) Places ±0.00 (±0.07) Do Not Scale Drawing Figure - PTH000 Part Numbering Figure - Tape Dimensions 0.1 (.0) PICK POINT P x = 9.9 (.0) 1.8 (.0). Safety Information P0 x =. (90.0) 0.09 (.0) Pick Point 0.9 (.).9 (17).1 Safety Standards and Approvals All models will have full international safety approval including EN090 and UL/cUL190. Models have been submitted to independent safety agencies for approval. Dimensions in Inches (mm) Material: Black Conductive PS Supplied with Snap on lid in clear conductive PS 1.8 (.0) Figure - Tray 0.9 (1.0). Fuse Information Any suitable value fuse (based on the input ratings) maybe used in the unearthed input line. However this is not required for compliance with safety.. Safety Considerations The converter must be installed as per guidelines outlined by the various safety agency approvals, if safety agency approval is required for the overall system.

6 PTH000 Single Series Application Note 1. Operating Information.1 Overtemperature Protection (OTP) Only the PTHxx00 and PTHxx00 series of products have overtemperature protection. These products have an on-board temperature sensor that protects the module s internal circuitry against excessively high temperatures. A rise in the internal temperature may be the result of a drop in airflow, or a high ambient temperature. If the internal temperature exceeds the OTP threshold (see datasheet specifications), the module s Inhibit control is automatically pulled low. This disables the regulator allowing the output voltage to drop to zero. (The external output capacitors will be discharged by the load circuit). The recovery is automatic, and begins with a soft-start power up. It occurs when the the sensed temperature decreases by about 10 C below the trip point. Note The overtemperature protection is a last resort mechanism to prevent thermal stress to the regulator. Operation at or close to the thermal shutdown temperature is not recommended and will reduce the longterm reliability of the module. Always operate the regulator within the specified Safe Operating Area (SOA) limits for the worst-case conditions of ambient temperature and airflow.. Overcurrent Protection For protection against load faults, all modules incorporate output overcurrent protection. Applying a load that exceeds the regulator s overcurrent threshold will cause the regulated output to shut down. Following shutdown a module will periodically attempt to recover by initiating a soft-start power-up. This is described as a hiccup mode of operation, whereby the module continues in the cycle of successive shutdown and power up until the load fault is removed. During this period, the average current flowing into the fault is significantly reduced. Once the fault is removed, the module automatically recovers and returns to normal operation. HORIZ SCALE: ms/div Figure 7 - Power-up Characteristic Vin (1 V/Div) Vout (1 V/Div) Iin ( A/Div) From the moment a valid input voltage is applied, the soft-start control introduces a short time delay (typically ms to 10 ms) before allowing the output voltage to rise. The output then progressively rises to the module s setpoint voltage. Figure 7 shows the soft-start power-up characteristic of the A output product (PTH000W), operating from a V input bus and configured for a. V output. The waveforms were measured with a A resistive load, with Auto- Track disabled. The initial rise in input current when the input voltage first starts to rise is the charge current drawn by the input capacitors. Power-up is complete within 1 ms.. Soft-Start Power-Up The Auto-Track feature allows the power-up of multiple PTH modules to be directly controlled from the Track pin. However in a stand-alone configuration, or when the Auto-Track feature is not being used, the Track pin should be directly connected to the input voltage, Vin (see Figure ) Up Dn 8 Track Sense V Vin PTH000 Vout.V Inhibit Adjust 1 7 Cin 1000µF Rset 98Ω 0.1W, 1% Cout 0µF Figure - Soft-Start Power-up When the Track pin is connected to the input voltage the Auto-Track function is permanently disengaged. This allows the module to power up entirely under the control of its internal soft-start circuitry. When power up is under soft-start control, the output voltage rises to the set-point at a quicker and more linear rate.

7 Application Note 1 7. Feature Set OUTPUT VOLTAGE SET-POINT RESISTOR VALUES 7.1 Adjusting the Output Voltage of the PTH000 The V o adjust control (pin ) sets the output voltage of the PTH000 product to a value higher than 0.8 V. The adjustment range (. V input) is from 0.8 Vdc to. Vdc (1). The adjustment method requires the addition of a single external resistor, R set, that must be connected directly between the V o Adjust and pins (). Table gives the preferred value for the external resistor for a number of standard voltages, along with the actual output voltage that this resistance value provides. For other output voltages the value of the required resistor can either be calculated using the following formula, or simply selected from the range of values given in Table. Figure 8 shows the placement of the required resistor. V out Standard R set (Preferred Value) V out (Actual). V.1 kω.0 V.0 V.1 kω.010 V 1.8 V.9 kω 1.80 V 1. V 8.87 kω 1.0 V 1. V 17. kω 1.0 V 1.0 V. kω 1.00 V 0.8 V Open 0.8 V Table - Preferred Values of R set for Standard Output Voltages V IN V IN Inhibit PTH000W Track 1 V O V OUT Va Req d Rset Va Req d Rset Va Req d Rset Open kω kω kω kω kω kω kω kω kω kω kω kω kω kω kω kω kω kω kω.0.91 kω kω kω.10. kω kω kω.1. kω kω kω.0. kω kω kω..0 kω kω kω.0.8 kω kω kω..7 kω kω kω.0.1 kω kω 1..9 kω.. kω kω kω.0. kω kω Notes: 1 Modules that operate from a. V input bus should not be adjusted higher than. V. Use a 0.1 W resistor. The tolerance should be 1%, with temperature stability of 100 ppm/ºc (or better). Place the resistor as close to the regulator as possible. Connect the resistor directly between pins and 1 using dedicated PCB traces. Never connect capacitors from V o Adjust to either or V out. Any capacitance added to the V o Adjust pin will affect the stability of the regulator. Table - Output Voltage Set-point Resistor Values 7. Output ON/OFF Inhibit For applications requiring output voltage ON/OFF control,each series of the PTH family incorporates an output Inhibit control pin. The inhibit feature can be used wherever there is a requirement for the output voltage from the regulator to be turned Off. C IN 100 µf (Required) R SET 1 % 0.1 W C OUT 100 µf (Optional) The power modules function normally when the Inhibit pin is left open-circuit, providing a regulated output whenever a valid source voltage is connected to Vin with respect to. Figure 9 shows the typical application of the inhibit function. Note the discrete transistor (Q1). The Inhibit control has its own internal pull-up to Vin potential. An open-collector or open-drain device is recommended to control this input. Figure 8 - Adjust Resistor Placement Turning Q1 on applies a low voltage to the Inhibit control pin and disables the output of the module. If Q1 is then turned off, the module will execute a soft-start power-up sequence. A regulated output voltage is produced within 0 ms. Figure 10 shows the typical rise in both the output voltage and input current, following the turnoff of Q1. The turn off of Q1 corresponds to the rise in the waveform, Q1 V DS. The waveforms were measured with a A load. 7

8 PTH000 Single Series Application Note 1 Vin Cin 70µF 1 = Inhibit PTH0010W 1 7 Vo Sense Q1 BSS18 Rset 1%, 0.1W Vout Cout 0µF L O A D Notes: 1 The soft-start cycle is a relatively short period (up to 0 ms) that immediately follows either the application of a valid input source voltage, or the release of a ground signal at the Inhibit pin To ensure that the regulator does not sink current when power is first applied (even with a ground signal applied to the Inhibit control pin), the input voltage must always be greater than the output voltage through-out the power-up and power-down sequence. The Auto-Track function can be disabled at power up by immediately applying a voltage to the module s Track pin that is greater than its set-point voltage. This can be easily accomplished by pulling the Track pin up to Vin through a 1 kω resistor. Figure 9 - Typical Application of the Inhibit Function Figure 10 - Typical Rise in Output Voltage and Input Current 7. Pre-Bias Start-up Capability Only selected products in the PTH family incorporate this capability. Consult Table 1 to identify which product series are compliant. In complex digital systems an external voltage can sometimes be present at the output of the module during power up. This voltage may be backfed through a dual supply logic component, such as an FPGA or ASIC. Another path might be via a clamp diode (to a lower supply voltage) as part of a power-up sequencing implementation Although the PTH family of modules can sink current under steadystate operating conditions, those that incorporate this capability will not do so during the soft-start cycle 1, or whenever the Inhibit pin is held low. However, to ensure the satisfactory operation of this feature certain conditions must be maintained during the application of input power. Note The pre-bias start-up feature is not compatible with Auto-Track. This is because when the module is under Auto-Track control, it is fully active and will sink current if the output voltage is below that of a back-feeding source. Therefore to ensure a pre-bias hold-off, one of the following two techniques must be followed when input power is first applied to the module. The Auto-Track function must either be disabled, or the module s output held off using the Inhibit pin. The latter allows Auto-Track s internal RC charge ramp to rise above the setpoint voltage. 8

9 Application Note 1 8. Thermal Information 8.1 Thermal Reference Points The electrical operating conditions namely: Input voltage, V in Output voltage, V o Output current, I o determine how much power is dissipated within the converter. The following parameters further influence the thermal stresses experienced by the converter: Ambient temperature Air velocity Thermal efficiency of the end system application Parts mounted on system PCB that may block airflow Real airflow characteristics at the converter location 8. Thermal Test Set-up All of the data was taken with the converter soldered to a test board which closely represents a typical application. The test board is a 1. mm, eight layer FR pcb with the inner layers consisting of oz power and ground planes. The top and bottom layers contain a minimal amount of metalisation. A board to board spacing of 1 inch was used. The data represented by the 0 m/s curve indicate a natural convection condition i.e. no forced air. However, since the thermal performance is heavily dependent upon the final system application, the user needs to ensure the thermal reference point temperatures are kept within the recommended temperature rating. It is recommended that the thermal reference point temperatures are measured using either AWG # or #0 gauge thermocouples or an IR camera. In order to comply with stringent Artesyn de-rating criteria, the ambient temperature should never exceed 8 C. Please contact Artesyn Technologies for further support. 8. Safe Operating Area Curve Thermal characterisation data is presented in the datasheet in a safe operating area curve format which is repeated here in Figure 11. This SOA curve shows the load current versus the ambient air temperature and velocity. 90 TEMPERATURE (ºC) LFM Nat conv OUTPUT CURRENT (A) Figure 11 - Safe Operating Curve PTH000W V out =. V 9

10 PTH000 Single Series Application Note 1 9. Use in a Manufacturing Environment 9.1 Recommended Land Pattern It is recommended that the customer uses a solder mask defined land pattern similar to that shown in Figures 1 and (.0) Figure 1 - Recommended Land Pattern (Through - Hole Model) (.0) 1 Recommended keep out area 1 Recommended keep out area (.1) 0.70 (19.0) (.1) 0.70 (19.0) ø0.0 (1.0) Places 0. (1.9) Figure 1 - Recommended Land Pattern (Surface Mount Model) Power pin connection should utilize four or more vias to the interior power plane of 0.0 (0.) I.D. per input, ground an doutput pin (or the electrical equivalent. As a surface-mount power component, interconnection to internal power planes will typically be required. This is accomplished by placing a number of vias between the SMT pad and the relevant plane. The number and exact location of these vias should be determined based on electrical resistivity, current flow and thermal requirements (.0) 0.7 (9.) ø0.08 (.1) Places Paste screen opening: 0.80 (.0 to 0.8 (.1) Paste screen thickness: 0.00 (0.10) (.0) 0.7 (9.) 0. (1.9) 10. Auto-Track 10.1 Auto-Track Function The Auto-Track function is unique to the PTH family, and is available with the all Point-of-Load Alliance (POLA) products. Auto- Track was designed to simplify the amount of circuitry required to make the output voltage from each module power up and power down in sequence. The sequencing of two or more supply voltages during power up is a common requirement for complex mixed-signal applications, that use dual-voltage VLSI ICs such as DSPs, microprocessors, and ASICs. 10. How Auto-Track Works Auto-Track works by forcing the module s output voltage to follow a voltage presented at the Track control pin. This control range is limited to between 0 V and the module s set-point voltage. Once the track-pin voltage is raised above the set-point voltage, the module s output remains at its set-point 1. As an example, if the Track pin of a. V regulator is at 1 V, the regulated output will be 1 V. But if the voltage at the Track pin rises to V, the regulated output will not go higher than. V. As the regulated output from the module simply follows the voltage at the Track pin, it is able to track virtually any voltage source during the power-up sequence. This can be the rising voltage of an externally generated master ramp waveform, or the output voltage from another power supply circuit. For convenience, each Track pin is also provided with an internal RC charge circuit that can produce a compatible voltage ramp from the input source voltage. 10. Typical Application The basic implementation of Auto-Track allows for simultaneous voltage sequencing of a number of Auto-Track compliant modules. Connecting the Track control pins of two or more modules forces the Track control of all modules to follow the same collective RC ramp waveform, and allows them to be controlled through a single transistor or switch; Q1 in Figure 1. To initiate a power-up sequence, it is recommended that the Track control be first pulled to ground potential. This should be done at or before input power is applied to the modules, and then held for at least 10ms thereafter. This brief period gives the modules time to complete their internal soft-start initialization. Applying a logic level high signal to the circuit s ON/OFF Control turns Q1 on and applies a ground signal to the Track pins. After completing their internal softstart intialization, the output of all modules will remain at zero volts while Q1 is on. 10 ms after a valid input voltage has been applied to the modules, Q1 may be turned off. This allows the track control voltage to automatically rise toward to the modules' input voltage. During this period the output voltage of each module will rise in unison with other modules, to its respective set-point voltage. Figure 1 shows the output voltage waveforms from the circuit of Figure 1 after the ON/OFF Control is set from a high to a low-level voltage. The waveforms, V o 1 and V o represent the output voltages from the two power modules, U1 (. V) and U (.0 V) respectively. V o 1 and V o are shown rising together to produce the desired simultaneous power-up characteristic. 10

11 Application Note 1 The same circuit also provides a power-down sequence. Power down is the reverse of power up, and is accomplished by lowering the track control voltage back to zero volts. The important constraint is that a valid input voltage must be maintained until the power down is complete. It also requires that Q1 be turned off relatively slowly. This is so that the Track control voltage does not fall faster than Auto-Track's slew rate capability, which is V/ms. The components R1 and C1 in Figure 1 limit the rate at which Q1 can pull down the Track control voltage. The values of 100 kω and 0.07 µf correlate to a decay rate of about 0. V/ms. The power-down sequence is initiated with a low-to-high transition at the ON/OFF Control input to the circuit. Figure 1 shows the powerup and power-down waveforms. As the Track control voltage falls below the nominal set-point voltage of each power module, then its output voltage decays with all the other modules under Auto-Track control. Notes on the Use Of Auto-Track 1. The Track pin voltage must be allowed to rise above them module s set-point voltage before the module can regulate at its adjusted set-point voltage.. The Auto-Track function will track almost any voltage ramp during power up, and is compatible with ramp speeds of up to V/ms.. The absolute maximum voltage that may be applied to the Track pin is V in.. The module output will not follow the voltage at the Track pin until the module has completed its soft-start cycle. The softstart-cycle takes up to about 0 ms to complete. During this time it is recommended that the Track pin be held at ground potential.. After the soft-start sequence is complete, the module is capable of both sinking and sourcing current when following the voltage at the Track pin. Figure 1 - Power Up & Power Down Waveforms U V Vin Track PTH000W Vo Vo1 =.V Cin Inhibit 1 7 R 98 Cout On/Off Control 1 = Power Down 0 = Power Up C1 0.07µF Q1 BSS18 U 10 Vin 9 8 Track PTH0010W Vo Vo= V R1 100k Cin Inhibit 1 7 R k1 Cout 0V Figure 1 - Sequenced Power Up and Power Down Using Auto-Track Application Note Artesyn Technologies 00 The information and specifications contained in this Application Note are believed to be correct at time of publication. However, Artesyn Technologies accepts no responsibility for consequences arising from printing errors or inaccuracies. The information and specifications contained or described herein are subject to change in any manner at any time without notice. No rights under any patent accompany the sale of any such product(s) or information contained herein. 11